Tiny kicks and punches in the womb help babies understand their new bodies

Researchers measuring the brainwaves of newborn babies have discovered that a baby's kicks are likely a way for the infant to map and begin to understand its body. The study could help doctors develop better techniques for looking after premature babies.

The research was a collaboration between University College London (UCL) and the University College London Hospitals (UCLH). Nineteen newborns were involved in the study, each of which was observed using a non-invasive technique known as electroencephalography (EEG), which tracks the brain activity of an individual through electrodes placed on the scalp.

The infants ranged between 31 and 42 weeks corrected gestational age. For a premature baby, the corrected gestational age is essentially a combination of the period during which the baby was in the womb, plus the amount of time that had elapsed since birth.

It was discovered that each time a baby made an involuntary hand movement, a pattern of fast brainwaves fired in the infant's left-brain hemisphere, which is known to process the sensation of touch for the hand. This suggests that such movements in the late stages of a pregnancy, known as the third trimester, are used to create a map, or sense understanding of an infant's body.

"Spontaneous movement and consequent feedback from the environment during the early developmental period are known to be necessary for proper brain mapping in animals such as rats," says study author Dr Lorenzo Fabrizi of the UCL Department of Neuroscience, Physiology and Pharmacology. "Here we showed that this may be true in humans too."

The brainwaves related to the mapping process were observed to be stronger in babies that were born very prematurely, and so would ordinarily still be protected in the womb. The activity gradually faded, and generally ceased altogether by the time the child had come full-term at roughly 41 corrected gestational weeks, though the corresponding movements remained.

Newborns spend a lot of time in active rapid eye movement (REM) sleep, during which isolated limb movements have been observed to occur. The amount of active sleeping significantly drops off around the same time that the body-mapping brainwaves fade.

This suggests that active sleeping provides the best environment in which a baby can get to know its body, and supports previous studies stating that such restive periods should be protected as much as possible in babies that have been born prematurely.

"We think the findings have implications for providing the optimal hospital environment for infants born early, so that they receive appropriate sensory input," comments Kimberley Whitehead of the UCL Department of Neuroscience, Physiology and Pharmacology, and co-author of the study. "For example, it is already routine for infants to be 'nested' in their cots – this allows them to 'feel' a surface when their limbs kick, as if they were still inside the womb."